1. Field of Invention
The present invention relates to the design and manufacture of an integrated circuit (IC), and particularly to a method for making a photomask layout.
2. Description of Related Art
As the level of integration of integrated circuits is increased, the demand for increasing the feature density or reducing the pitch size becomes the mainstream in the semiconductor industry, and the key technology is in photolithography. In the photolithographic module, the accuracy in the pattern transferring process from a photomask to a wafer is quite important.
When the line-width drops to one half or less of the wavelength of the light source for exposure, several correction and verification steps are required to perform to the whole graphic data of a photomask, so as to reduce the deviation of the critical dimension on the wafer during the pattern transferring process. However, the graphic data system (GDS) file of the photomask used in advanced IC processes easily has a size up to hundreds of gigabytes, so it is very time-consuming to perform the said correction and verification steps.